Ultrafast laser spectroscopy may open door to efficient clean industrial fuels

Carbon dioxide (CO₂) is an abundant waste product that can be converted into energy-rich byproducts such as carbon monoxide. However, this process needs to be boosted in efficiency for it to work on a global industrial scale. Electrocatalysts have shown promise as a potential way to achieve this required efficiency change in CO₂ reduction, but the mechanisms by which they operate are often unknown, making it hard for researchers to design new ones in a rational manner. New research by researchers at the University of Liverpool (Liverpool, England), in collaboration with Beijing Computational Science Research Center (Beijing, China) and STFC Rutherford Appleton Laboratory (Didcot, England), demonstrates a laser-based technique that can be used to study the electrochemical reduction of CO₂ in situ and provide much-needed insights into these complex chemical pathways.

The researchers used vibrational sum-frequency generation (VSFG) spectroscopy, coupled with electrochemical experiments, to explore the chemistry of the Mn(bpy)(CO)3Br catalyst, which is one of the most promising and intensely studied CO₂ reduction electrocatalysts. In VSFG spectroscopy, femtosecond infrared pulses and visible picosecond pulses are focused on regions of interest, causing sum-frequency generation (SFG) of light to be generated in the interfaces between the regions—interfacial vibrational modes produce resonant enhancement of the sum-frequency light. Using VSFG, the researchers observed key intermediates that are only present at an electrode surface for a very short time—something that has not been achieved in previous experimental studies. Following from this research, the team is now working to further improve the sensitivity of the technique and is developing a new detection system that will allow for a better signal-to-noise ratio. Reference: G. Neri et al., Nat. Catal. (2018); https://doi.org/10.1038/s41929-018-0169-3.